A Study of the Reactivity of Secondary Phosphanes with Radical Sources: A New Dehydrocoupling Reaction

The reactions of secondary phosphanes with radical sources have been investigated. A stoichiometric dehydrocoupling of Ph(2)PH with 1,1'-azobis[cyclohexane-1-carbonitrile] (VAZO (R) 88) affords tetraphenyldiphosphane in good yields, whilst reduction of the nitrosyl function was observed upon using 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). Dialkylphosphane-borane adducts also undergo a dehydrocoupling reaction in the presence of VAZO (R) 88 to form R(4)P(2).